server/app/Utils/helpers.php

<?php

function sysConfig($key)
{
    if (is_array($key)) {
        return \App\Model\SystemConfig::whereIn('config_key', $key)->pluck('config_value', 'config_key') ?? [];
    }
    if (is_string($key)) {
        return \App\Model\SystemConfig::where('config_key', $key)->value('config_value') ?? null;
    }
}